CFD Approach for Off-Design Efficiency Improvement of Double Suction Centrifugal Pump

The energy consumed by a large pump to transport the water has a dominant role in pumping system and hence the efficiency of the pump is of great concern to both manufacturer and customer in large size pumps. The pumps mostly operate at off-design conditions and hence at lower performance. A little improvement in the efficiency of pump will save huge amount of energy and money. In order to improve performance of double suction centrifugal pump, especially at off-design conditions, systematic and validated computational fluid dynamics (CFD) approach had been used to assess the flow behavior in suction casing, impeller and delivery casing of an existing pump for identification of geometrical locations for performance improvement. The head losses and flow pattern in the individual part of the pump were studied and identified the locations for performance improvement and accordingly, the geometry of pump components and surface roughness were modified. There was an increase of normalized head and efficiency by 4.5% and 3.1% respectively at duty point as compared to the CFD results of existing pump. The substantial increase in head and efficiency was also achieved at off-design conditions for both existing and smooth surfaces.